Fuel pump system



Nov. 4, 1969 T, H. THOMPSON FUEL PUMP SYSTEM Filed Dec. 4. 196'? TOM H. THOMPSON INVENTOR M 2E? M) e. M W

ATTORNEYS United States Patent 3,476,145 FUEL PUMP SYSTEM Tom H. Thompson, Dearborn Heights, Mich, assignor to Ford Motor Company, Dearborn, Mich, a corporation of Delaware Filed Dec. 4, 1967, Ser. No. 687,516 Int. Cl. F04f 7/00 US. Cl. 137-565 1 Claim ABSTRACT OF THE DISCLOSURE An engine camshaft reciprocated fuel pressure generator intermittently supplies a fuel pressure pulse through a line to a fuel pump piston submerged in the fuel in a motor vehicle fuel tank, the pulse moving the piston to fill a chamber in the piston, the fuel in the chamber subsequently being displaced back into the supply line to not only return the pulse generator to its initial position, but supply fuel to an inlet line; the pump piston containing a number of one-way check valves permitting the above action.

This invention relates, in general, to a fuel pump system for an internal combustion engine. More particularly, it relates to an engine driven fuel pump that is submerged in the fuel tank of a motor vehicle.

In the past, most motor vehicle type fuel pumps have been of the integral unit, engine camshaft driven, type. The engine driven portion and the fuel pump per se generally were enclosed in a common housing adjacent to the engine camshaft and connected to the fuel tank and to the carburetor by a plurality of hoses. A characteristic of this type of pump is that it is of the negative pressure type; that is, it operates on an intake and a pressure stroke, the intake stroke creating a suction or negative pressure to draw fuel from the tank through the line or hose to the pump proper, from which it is discharged on the pressure stroke to the carburetor. A system of this type encourages vapor lock in the intake line, which shuts off the supply of fuel to the carburetor.

It has been proposed to use electric fuel pumps that are submerged in the fuel in the motor vehicle fuel tank. These have the advantage of providing a positive pressure in the system at all times, and therefore, minimize the vapor lock problem. However, a pump of this type will fail with a current failure.

It is an object of the invention to provide a fuel pump system that combines the advantages of both the conventional engine driven mechanical fuel pump and the electric fuel pump submerged in the fuel tank by providing a mechanical fuel pump that is submerged in the fuel tank and driven by a remotely located engine camshaft operated pulse generator.

It is another object of the invention to provide a fluid pump system consisting of a fluid pressure pulse generator and a mechanical fluid pump submerged in the fluid, the two being connected by a single fluid line that also serves as a fluid supply line to an additional element or device.

It is a further object of the invention to provide a fuel pump system that includes an engine cam operated fuel pressure pulse generator that alternately pressurizes and depressurizes fuel in a chamber of the pulse generator; the chamber being connected by a single fuel line both to a carburetor and to a fuel pump submerged in a motor vehicle fuel tank; the fuel pump containing a reciprocatable piston having a plurality of one-way check valves permitting fuel in the line to move the pump piston through an intake stroke, during the pressure stroke of the pulse generator, to transfer fuel from the tank to a chamber in the piston; and permitting a return movement of the piston to expel fuel from the chamber under pres- "ice sure into the single fuel line; the increase in pressure initially returning the pulse generator to its fuel depressuriz ing position and subsequently opening the line to the carburetor.

Other objects, features, and advantages of the invention will become apparent upon reference to the succeeding detailed description thereof, and to the drawings illustrating schematically a cross-sectional View of a fuel pump system embodying the invention.

The lower part of the figure shows a portion 10 of a fuel or gasoline tank commonly attached to the body portion of a motor vehicle. The bottom of the tank has a central opening 12 through which is inserted the upper portion ofa stepped diameter, hollow, fuel pump housing 16. The housing includes a lower portion 18 that is sealingly secured to the bottom of tank 10 by bolts or other suitable means, not shown. The two portions are threadedly interconnected at 19.

The stepped diameter of housing 16 defines an annular lowerfuel reservoir or chamber 20 that is connected at all times with the fuel in tank 10 by a plurality of passages 22. The chamber slidably and sealingly receives the larger diameter part 24 of a stepped diameter piston 26, the smaller diameter portion 28 being slidable within housing upper portion 14. A flexible bellows 30 sealingly connects the upper face 32 of the piston to a fuel port or passage 34 formed in the housing, for a purpose to be described later. Vent of fuel from the space 36 between the housing and bellows is afforded by a plurality of ports 38. Suitable ring seals 40 and 42 sealingly separate the space 36 from the upper face 44 of lower piston land 24. A spring 45 normally biases piston 26 to the piston shown, collapsing bellows 30.

The two piston portions 24 and 28 have a central passageway or bore 46 that is intersected by a cross bore 48. The cross bore is in communication at all times with the annular clearance space 50 between the top face 44 of piston part 24 and the lower face of a shoulder 52 of housing 16. Space 50 constitutes a fuel chamber that increases in area as piston 26 moves downwardly.

Control of flow of fuel from lower chamber 20 to chamber 50 is provided by a combination fuel inlet check and line pressure release valve 54. The latter is slidable in an enlargement 56 of central bore 46, and is spring biased to a closed position against a seat 58. Seat 58 is formed in a plug threaded to the piston and having a central bore 60.

Check valve 54 has ports 62 and 64 at opposite ends joined by a recess containing a ball pressure relief valve 66. The ball is spring biased upwardly to close port 62 below a predetermined high pressure in cross passage 48.

Flow of fuel between space 50 and the interior of bellows 30 is controlled by a second one-way ball check valve 68, the latter being spring biased against a conically formed seat in an enlarged portion of bore 46, as shown.

Port 34 is connected by a line 70 to an engine driven pulse generator 72. The latter includes a cylindrical-like housing 74 attached to an upper plate-like member 76 and having a lower drilled passage portion 78. A cylindrical recess 80 interconnects passage 78 to the interior of housing 74, and slidably receives the stem 82 of a piston 84. The lower face of the piston is sealingly connected to the lower part of the housing portion by a flexible bellows 86. Piston 84 is reciprocated by a cam 86 attached to a right angle lever 90 pivotally mounted at 92 within an opening in plate member 76.

The interior of bellows 86 constitutes a fuel chamber 93, that communicates With passage or line 78 through a port 94. The fuel chamber also communicates at times with passage 78 through recess 80 and central and cross bores 95 and 96 in stem 82. The uppermost portion 98 of passage 78 is, in this case, adapted to be connected to a line 100 leading to carburetor fuel bowl, not shown.

In this instance, lever 90 is adapted to be moved intermittently from left to right, as seen in the figure, to effect a reciprocation of piston 84, by a cam, not shown, on the cam-shaft of an internal combustion engine.

Operation Assume that the cam (not shown) that abuts lever 90 is rotated so that the lever abuts the base circle of the cam. Also assume that fuel tank is filled with fuel, and the pulser chamber 93 and lines 100, 98, and 70 are filled with fuel through an external plug, not shown. At this time, no force will be exerted on pulse generator lever 90 attempting to move it to the right, and thus the force of fuel pump return spring 45 will position the piston part 24 as shown to abut the shouldered portion 52 of housing 16. Fuel from tank 10 will flow through passages 22 to fill chamber 20, and pump chamber 50 and bores 48 and 46 will contain fuel under no pressure.

Assume now that the cam rotates to position the ramp surface of the cam to engage pulse generator lever 90. The lever begins pivoting and moving piston 84 to the right to compress bellows 86. The movement of the piston will move stem 82 to cut off passage 98 and force fuel in chamber 93 through the port 94 to pressurize lines 78 and 70. This pressure increase acting on the top face of piston part 28 will maintain ball check valve 68 seated and force piston 26 downwardly against the force of return spring 45. The immediate increase in pressure in lower chamber 20 will unseat the inlet valve 54 and permit displacement of fuel from chamber 20 through port 60 and around valve 54 into bores 46 and 48 and into chamber 50. As piston 26 moves downwardly, therefore the fuel fills the increasing volume of chamber 50.

As soon as the cam nose portion rotates out of contact with lever 90, the pressure in pulse generator chamber 93 will begin to decay and permit pump return spring 45 to begin moving piston 26 upwardly. The force of the fuel in chamber 50 now increases above that of chamber 20, seats inlet valve 54, and opens upper check valve 68. This allows fuel to be displaced from chamber 50 into line 70 to expand bellows 86. When the base circle of the cam contacts the plunger lever 90, the piston stem 82 will have been moved sufficiently to the left, towards the position shown, to permit fuel to flow from line 70, 78 to the carburetor supply line 100. This is accomplished due to the excess fuel pressure at this time as a result of the differential area of the piston portions 24 and 28 so that fuel will continue to flow to the carburetor until piston portion 24 is returned to the position shown in the figure. By this time, the cam will have rotated to a position to again start the cycle.

Thus, it will be seen that, first; the engine driven pulsator 72 moves through an intake or fuel pressurizing stroke displacing fuel to force the pump piston 26 through an intake stroke displacing fuel from chamber 20 to chamber 50 within the piston, and that, secondly; when the cam begins to relax the force on pulse generator piston 84, the pump piston return spring 45 will move pump piston 26 upwardy to displace fuel from chamber 50 into line 70, and extend bellows 86 and return pulsator piston 84 to the initial position shown, and force fuel through line 100.

While the invention has been illustrated and described in its preferred embodiment, it will be clear to those skilled in the arts to which it pertains that many changes and modifications may be made thereto without departing from the scope of the invention.

I claim:

1. A fuel pump system for a motor vehicle having an engine driven camshaft and a cam thereon, comprising in combination, a fuel tank containing fuel, a fuel pump in said tank in said fuel, and a camshaft cam reciprocated fuel force applying pulse generator remotely located therefrom but operably connected thereto, said generator, including a body portion containing a fuel chamber, reciprocatable force applying means in said body portion movable alternately by said cam and fuel pressure in fuel pressurizing and depressurizing directions, respectively, said fuel pump including a housing means securing said housing to said fuel tank in a manner wherein a first portion of said housing extends into said fuel tank and a second portion extends below and beyond said tank, passage means connecting the fuel in said tank to the second portion of said housing below said tank whereby fuel flows at all times to said portion, said housing having a stepped diameter hollow interior slidably receiving a stepped diameter piston therein in a nesting manner whereby fluid chambers are formed on opposite sides of the larger diameter portions of said piston that vary in area from essentially zero to a maximum as a function of the reciprocation of said piston, a fuel line passing through said generator body portion and communicating with said chamber and having a portion extending to a point beyond said body portion, said line portion being blocked by said force applying means upon movement of the latter in a fuel pressurizing direction and being unblocked upon movement of the force applying means in the fuel depressurizing direction, means connecting the remaining portion of said line to the smaller diameter portion of said fuel pump piston to act thereon and move said piston in an intake stroke direction upon movement of said force applying means in a fuel pressurizing direction, said latter means constituting the sole interconnection between said generator and fuel pump, expandable bellows means sealingly connecting said smaller diameter portion to said housing isolating the piston portions from one another, means biasing said piston in a pressure stroke direction, said piston containing a plurality of unidirectional valve means operable upon movement of said piston in said intake stroke direction to connect the fuel in said housing to said chamber and operable upon movement of said piston in the said pressure stroke direction to force the fuel in said chamber from said pump through said line under pressure, the pressure of said fuel moving said force applying means in a fuel depressurizing direction and unblocking said line portion permitting fuel flow through said line to a point beyond said body portion.

References Cited UNITED STATES PATENTS 1,957,360 5/1934 Schmidt.

2,058,455 10/1936 Huff.

2,286,926 6/ 1942 Parenti.

3,065,784 11/1962 Thompson.

ROBERT M. WALKER, Primary Examiner US. Cl. X.R. 

